Aqueous pigment pastes containing metallic pigments and the use thereof for producing substances for decorative aqueous coatings

ABSTRACT

An aqueous pigment paste free from binders and grinding resins, comprising based on its overall amount
     (A) from 15 to 40% by weight of at least one metal pigment, especially an aluminum pigment,   (B) from 0.45 to 0.75% by weight of at least one non-associative thickener comprising at least one methacrylate copolymer based on C 1 -C 6  alkyl(meth)acrylate and (meth)acrylic acid,   (C) from 0.1 to 0.4% by weight of at least one organic amine,   (D) from 0.5 to 8% by weight of at least one nonionic surfactant, and   (E) at least 50% by weight of water;
 
its use for preparing aqueous coating materials, and processes for the preparation.

This application is a National Phase Application of Patent ApplicationPCT/EP02003/009267 filed on 21 Aug. 2003, which claims priority to DE102 40 972.2, filed on 2 Sep. 2002.

The present invention relates to novel aqueous pigment pastes comprisingmetal pigments, especially aluminum pigments, but free from binders andgrinding resins. The present invention further relates to the use of thenovel aqueous pigment pastes comprising metal pigments but free frombinders and grinding resins for producing aqueous effect coatingmaterials. The present invention additionally relates to a novel processfor producing aqueous effect coating materials.

The use of metal or aluminum effect pigments in aqueous basecoatmaterials is well established.

On account of their comparatively high sensitivity to mechanicaleffects, however, metal pigments and especially aluminum pigments causeproblems on incorporation into aqueous coating materials, especiallyaqueous basecoat materials.

The metal pigments are normally pasted or dispersed in organic solvents,with or without binders.

A disadvantage is that the pigment pastes in question have only a verylimited shelf life of not more than a few days. After that time,settling occurs and inhomogeneities and coagulum are formed, reducingthe quality of the multicoat color and/or effect paint systems byclouding, among other phenomena. For industrial coating on the line atthe automaker's plant as well, the inadequate shelf life is a majorproblem. Accordingly, the pigment pastes cannot be produced in sizeableamounts for holding in stock, although this would be desirable oneconomic grounds. The transport-ability of the pigment pastes alsoleaves much to be desired. As a result, the possibility of preparing thepigment pastes at one production site with optimum production conditionsand transporting them to the customers is closed off. Moreover, for theaftertinting of aqueous basecoat materials, the pigment pastes have tobe prepared anew each time.

It is an object of the present invention to provide a novel aqueouspigment paste comprising metal pigments, especially aluminum pigments,which no longer has the disadvantages of the prior art but which insteadcan be prepared simply, without damage to the mica pigments,transportably, storably, and stably with a minimum level of organicsolvents, additives, and polymeric binders. Preferably, the novelaqueous pigment paste comprising metal pigments ought to be storable forup to 3 months without settling and without the formation ofinhomogeneities or coagulum.

It ought to be possible to prepare the novel aqueous pigment pastecomprising metal pigments at a production site which offers optimumconditions and to transport it to the customers, especially theautomakers. Accordingly, the stockholding complexity should be reducedsignificantly. Moreover, the novel aqueous pigment paste comprisingmetal pigments ought to be able easily to withstand shearing in thecircuits of the coating plants without being damaged.

The novel aqueous pigment paste comprising metal pigments is intended toallow the preparation of storable, transportable aqueous coatingmaterials, especially aqueous basecoat materials, which are stable inshade, stable in effect, and easy to apply, and which give outstandingmulticoat color and/or effect paint systems of automobile quality (onthis point, see also European patent EP 0 352 298 B 1, page 15 line 42to page 17 line 40).

The invention accordingly provides the novel aqueous pigment pastecomprising metal pigments but free from binders and grinding resins,said paste comprising based on its overall amount

-   (A) from 15 to 40% by weight of at least one metal pigment,-   (B) from 0.45 to 0.75% by weight of at least one non-associative    thickener comprising at least one methacrylate copolymer based on    C₁-C₆ alkyl(meth)acrylate and (meth)acrylic acid,-   (C) from 0.1 to 0.4% by weight of at least one organic amine,-   (D) from 0.5 to 8% by weight of at least one nonionic surfactant,    and-   (E) at least 50% by weight of water,    and being referred to below as “pigment paste of the invention”.

The pigment paste of the invention may further comprise any of theadditives and further constituents commonly used in pigment pastesand/or coating materials.

The invention also provides for the novel use of the pigment paste ofthe invention for producing aqueous effect, especially color and effect,coating materials, referred to below as “inventive use”.

The invention provides not least the novel process for preparing anaqueous effect or color and effect coating material by mixing at leastone pigment paste with at least one aqueous mixing varnish comprising atleast one water-soluble and/or -dispersible binder and homogenizing theresulting mixture, which involves mixing at least one pigment paste ofthe invention with the mixing varnish in an amount such that theresulting aqueous effect or color and effect coating material comprisesbased on its overall amount

-   -   from 0.1 to 6% by weight of at least one metal pigment (A),    -   from 0.05 to 2% by weight of at least one non-associative        thickener (B) comprising at least one methacrylate copolymer        based on C₁-C₆ alkyl(meth)acrylate and (meth)acrylic acid, and    -   from 0.02 to 2.4% by weight of at least one nonionic surfactant        (D).

The novel process for preparing an effect coating material is referredto below as “process of the invention”.

In the light of the prior art it was surprising and unforeseeable forthe skilled worker that the object on which the present invention wasbased could be achieved by means of the pigment paste of the inventionwithout the occurrence of the disadvantages of the prior art, depictedat the outset.

The pigment paste of the invention was simple to prepare without damageto the metal pigments. It was substantially or entirely free fromorganic solvents, binders, and grinding resins. Additionally, onlycomparatively small amounts of additives were needed. Despite this, thepigment paste of the invention was surprisingly stable, transportable,and storable. A particular surprise was that the pigment paste of theinvention was storable for up to 3 months without settling and withoutthe formation of inhomogeneities or coagulum.

The pigment paste of the invention could be prepared at a productionsite offering optimum conditions, and transported to the customers,especially the automakers. In this way it was possible to reducesignificantly the complexity of stockholding for the customer. Moreover,the pigment paste of the invention could be sheared in the circuits ofthe coating plants readily without being damaged.

Surprisingly, the pigment paste of the invention gave storable,transportable aqueous coating materials, especially aqueous basecoatmaterials, which were stable in shade, stable in effect, and easy toapply.

The aqueous basecoat materials allowed the production of outstandingmulticoat effect, or color and effect, paint systems of automobilequality. According to European patent EP 0 352 298 B 1, page 15 line 42to page 17 line 14, this means that the multicoat paint systems inquestion had

-   (1) high gloss,-   (2) high distinctiveness of image,-   (3) high and uniform hiding power,-   (4) uniform dry film thickness,-   (5) high gasoline resistance,-   (6) high solvent resistance,-   (7) high acid resistance,-   (8) high hardness,-   (9) high abrasion resistance,-   (10) high scratch resistance,-   (11) high impact strength,-   (12) high intercoat adhesion and adhesion to the substrate, and-   (13) high weathering stability and UV resistance.

The pigment paste of the invention is free from binders and grindingresins. Regarding the term “binders”, refer to Römpp Lexikon Lacke undDruckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, “Binders”,pages 73 and 74. Grinding resins are used for dispersing pigments (cf.Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, NewYork, 1998, “Dispersing”, page 34) for the purpose of preparing pigmentpastes or pigment preparations (cf. Römpp Lexikon Lacke und Druckfarben,Georg Thieme Verlag, Stuttgart, New York, 1998, “Pigment preparations”,page 452). They are binders whose capacity for dispersing pigments isparticularly high.

In the context of the present invention, “free from binders and grindingresins” means that the pigment paste of the invention contains nobinders and no grinding resins or only amounts thereof so small thatthey do not characterize, and in particular do not adversely affect, theperformance properties of the pigment paste of the invention.

With preference, the pigment paste of the invention is also free fromorganic solvents. This means that the pigment paste of the inventioncontains only amounts of organic solvents so small that they do notcharacterize, and in particular do not adversely affect, the performanceproperties of the pigment paste of the invention. The amount of organicsolvents, based on the pigment paste of the invention, is preferablybelow 10%, more preferably below 5%, and with particular preferencebelow 1% by weight, and in particular is below the detection limit ofthe organic solvents.

The pigment paste of the invention comprises at least one metal pigment(A) and preferably at least two, more preferably at least three and inparticular two, metal pigments (A). By metal pigments are meant finelydivided metallic pigments, usually in the form of flakes, which arecommercialized as powders or pigment pastes. A distinction is madebetween metallic pigments and those metal effect pigments which fulfillfunctional roles, e.g., in corrosion protection, as conductive pigments,or for protecting against electromagnetic radiation (EMI shielding); seethe table. Besides the metallic pigments in flake form there are dustscomprising spherical particles (zinc dust, lead dust) and the dendriticcopper powder (cf. Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, Stuttgart, New York, 1998, p. 381 “metal pigments”).

Overview of Metal Pigments

Metallic pigments Functional pigments Aluminum pigments Lead dust Goldbronzes Zinc dust Copper powders Zinc pigments Conductive pigments

In the pigment paste of the invention, based on its overall amount, themetal pigments (A) are present in an amount of from 15 to 40% by weightand in particular 22% by weight. Advantageously, they are aluminumpigments.

Aluminum pigments (aluminum bronze, silver bronze) are metallic pigmentsin flake form which are produced from foundry aluminum of minimum purity99.5% (DIN EN 573-3; 1994-12) or pure aluminum of minimum purity 99.95%by the Hall or Hametag process. Aluminum pigments are used to provide aneffect (metallic effect), for example, in automotive topcoats, hammerfinishes, chrome effect finishes, and other effect coatings, and also inprinting inks. They are also used, however, as functional pigments incorrosion protection coatings (barrier effect), reflective coatingmaterials, and other specialty fields. One relatively new developmentrelates to effect pigments wherein the aluminum flake is coated with athin iron oxide layer (iron oxide-aluminum pigments). As a result ofinterference at this layer, the metallic effect is accompanied by acolor effect (cf. Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, Stuttgart, New York, 1998, p. 24 “Aluminum pigments”).

The pigment paste of the invention may further comprise at least onepigment other than the metal pigments (A), selected preferably from thegroup consisting of organic and inorganic pigments, color pigments,optical effect pigments, electrically conductive pigments, magneticpigments, magnetically shielding pigments, fluorescent pigments,phosphorescent pigments, anticorrosion pigments, and extender pigments,pigments having at least two of these properties, and nanoparticles,provided such an additional pigment does not adversely affect theperformance properties of the pigment paste of the invention. Withpreference, the pigment paste of the invention contains no furtherpigment.

Based on its overall amount, the pigment paste of the invention containsfrom 0.45 to 0.75% by weight, in particular from 0.5 to 0.7% by weight,of at least one, especially one, nonassociative thickener comprising atleast one methacrylate copolymer based on C₁-C₆ alkyl(meth)acrylate and(meth)acrylic acid, especially methacrylic acid. The thickener (B)preferably contains in copolymerized form at least two different C₁-C₆alkyl(meth)acrylate monomers. Based on its overall amount it containsmore preferably from 40 to 60% by weight of methacrylic acid incopolymerized form. The thickener (B) is used preferably in the form ofan aqueous dispersion. With particular preference, use is made of thedispersions of thickeners (B) such as are described, for example, inGerman patent applications DE 196 52 842 A 1, column 3 line 42 to column4 line 4, or DE 197 41 554 A 1, column 2 line 54 to column 3 line 15.Very particular preference is given to using an aqueous dispersion ofthe thickener (B) which is sold under the brand name Viscalex® HV 30 byAllied and has a thickener (B) content of 30% by weight.

Based on its overall amount, the pigment paste of the invention containsfrom 0.1 to 0.4% by weight, in particular from 0.2 to 0.3% by weight, ofat least one, especially one, organic amine (C). The amine (C) ispreferably selected from the group of the tertiary amines, preferably ofthe tertiary alkylamines, and especially of the tertiaryhydroxyalkylamines. Examples of suitable tertiary hydroxyalkylamines aretriethanolamine, methyldiethanolamine, and dimethylethanolamine,especially dimethylethanolamine.

Based on its overall amount, the pigment paste of the invention furthercontains from 0.5 to 8% by weight, in particular 0.61% by weight, of atleast one nonionic surfactant. Suitable nonionic surfactants (cf. RömppLexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, page 410,“Nonionic surfactants”) in accordance with the invention are surfactantswhose hydrophyllicity is brought about by polyether chains, hydroxylgroups, carboxamido groups, urethane groups and/or ester groups.Nonionic surfactants are commercial products and are sold, for example,under the brand name Tegodispers® 740 by Tego, under the brand nameHydropalat® 3037 by Cognis, or under the brand name Setalux® 6802 AQ 4by Akzo. Preference is given to using Tegodispers® 740 and Hydropalat®3037. Hydropalat® 3037 is a silicone-free surface-active levelingadditive for aqueous systems, with a hydroxyl number of from 73 to 83 mgKOH/g and a hydrolysis number (DGF C-V 3) of from 56 to 62. Tegodispers®740 is a nonionic modified fatty acid derivative free from aromatics,amine, and nonylphenol ethoxylate. Surfynol is especially suitable.

Based on its overall amount, the pigment paste of the invention notleast contains at least 50% by weight and preferably at least 52%, withparticular preference at least 54% by weight of water.

The pigment paste of the invention may further comprise customary andknown additives, such as customary coatings additives. It is, however, aparticular advantage of the pigment paste of the invention that it neednot contain any further additives in order to achieve the advantagesaccording to the invention.

The preparation of the pigment pastes of the invention requires nopeculiarities in terms of method but instead takes place in accordancewith the customary and known methods of preparing pigment pastes orpigment formulations by mixing of the above-described ingredients inappropriate mixing equipment such as stirred tanks, dissolvers,Ultraturrax, inline dissolvers, stirred mills, bead mills or extruders.The skilled worker is aided on the basis of his or her general artknowledge to select the techniques and equipment in such a way that theparticular metal pigments (A) to be dispersed are not damaged.

In accordance with the invention, the pigment paste of the invention isused for preparing aqueous effect, or color and effect, coatingmaterials, especially aqueous basecoat materials.

For this purpose, the pigment paste of the invention is mixed with atleast one aqueous mixing varnish and then the resulting mixture ishomogenized. This is preferably carried out using the techniques andequipment described above.

The mixing varnish comprises at least one water-soluble and/or-dispersible binder. The binder is preferably selected from the groupconsisting of random, alternating, and block, linear, branched, and combaddition (co)polymers of ethylenically unsaturated monomers orpolyaddition resins and/or polycondensation resins. Regarding theseterms, refer to Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, Stuttgart, New York, 1998, page 457, “Polyaddition” and“Polyaddition resins (polyadducts)”, and also pages 463 and 464,“Polycondensates”, “Polycondensation” and “Polycondensation resins”, andalso pages 73 and 74, “Binders”.

The addition (co)polymers of ethylenically unsaturated monomers arepreferably selected from the group consisting of (meth)acrylate(co)polymers and partially hydrolyzed polyvinyl esters, especially(meth)acrylate copolymers, and the polyaddition resins and/orpolycondensation resins are preferably selected from the groupconsisting of polyesters, alkyds, polyurethanes, polylactones,polycarbonates, polyethers, epoxy resin-amine adducts, polyureas,polyamides, polyimides, polyester-polyurethanes,polyether-polyurethanes, and polyester-polyether-polyurethanes,especially polyester-polyurethanes.

Very particular preference is given to using the binders such as areemployed in customary and known aqueous basecoat materials. Binders ofthis kind are described, for example, in German patent application DE196 52 842 A 1, column 2 line 53 to column 3 line 46, and in Germanpatent application DE 199 14 896 A 1, column 5 line 34 to column 11 line5.

The binders are used in the mixing varnish in the amounts which arecustomary and known for aqueous basecoat materials.

The mixing varnish may further comprise customary and known crosslinkingagents, and additives in the customary and known amounts such as aredescribed, for example, in German patent application DE 199 14 896 A 1,column 11 line 6 to column 16 line 16.

It is essential that in the process of the invention the pigment pasteof the invention is used in an amount such that the resulting aqueouseffect, or color and effect, coating material contains based on itsoverall amount

-   -   from 0.1 to 6% by weight of at least one of the metal pigments        (A),    -   from 0.05 to 2% by weight of at least one of the nonassociative        thickeners (B) comprising at least one methacrylate copolymer        based on C₁-C₆ alkyl(meth)acrylate and (meth)acrylic acid, and    -   from 0.02 to 2.4% by weight of at least one of the nonionic        surfactants (D).

The resulting aqueous coating materials, especially the aqueous basecoatmaterials, may be curable physically, thermally with self-crosslinkingand/or external cross-linking, with actinic radiation, or thermally andwith actinic radiation. By actinic radiation is meant near infrared(NIR), visible light, UV radiation or X-rays, especially UV radiation,and also corpuscular radiation, such as electron beams. Conjoint thermalcuring and curing with actinic radiation is also referred to by those inthe art as dual cure.

The aqueous basecoat materials are preferably used for producingmulticoat effect, or color and effect, paint systems on primed andunprimed substrates.

Suitable substrates include all surfaces to be coated which are notdamaged by curing of the coating systems present thereon using heat orheat and actinic radiation. Suitable substrates consist, for example, ofmetals, plastics, wood, ceramic, stone, textile, fiber composites,leather, glass, glass fibers, glass wool, rock wool, mineral-bound andresin-bound building materials, such as plasterboard and cement slabs orroof shingles, and also combinations of these materials. The surfaces ofthese materials may have already been painted or coated.

Accordingly, the aqueous basecoat materials are especially suitable forpainting motor vehicle bodies and parts thereof, the interior andexterior of motor vehicles, the interior and exterior of buildings,doors, windows, and furniture, and, in the context of industrialcoating, for the painting of parts made of plastic, especiallytransparent plastics parts, small parts, coils, containers, packaging,electrical components, and white goods, and also for the coating ofhollow glassware.

The aqueous basecoat materials are very suitable indeed for the original(OEM) finishing and refinish of motor vehicles, especially automobiles.

In the case of electrically conductive substrates, primers can be used,which are produced in a customary and known manner from electrocoatmaterials. Both anodic and cathodic electrocoat materials are suitablefor this purpose, but especially cathodic electrocoats.

The coating of the invention may also be used to paint primed orunprimed plastics such as, for example, ABS, AMMA, ASA, CA, CAB, EP, UF,CF, MF, MPF, PF, PAN, PA, PE, HDPE, LDPE, LLDPE, UHMWPE, PET, PMMA, PP,PS, SB, PUR, PVC, RF, SAN, PBT, PPE, POM, PUR-RIM, SMC, BMC, PP-EPDM andUP (codes according to DIN 7728T1) and polymer blends thereof, or thefiber reinforced composite materials produced using these plastics.

Nonfunctionalized and/or apolar substrate surfaces may be subjectedprior to coating in a known manner to a pretreatment, such as with aplasma or by flaming, or provided with a hydro primer.

The multicoat paint systems may be produced in a variety of ways.Preference is given to the wet-on-wet techniques described in Germanpatent application DE 199 30 664 A 1, page 15 lines 36 to 58, or inGerman patent application DE 199 14 896 A 1, column 2 line 15 to column3 line 24 and column 16 line 54 to column 18 line 54.

This is done using the customary and known techniques and equipment forthe application and curing of coating materials, especially aqueouscoating materials.

Owing to the outstanding distribution of the metal pigments (A) in thepigment paste of the invention, and its storage stability, the endresults are multicoat paint systems of outstanding shade stability andstability of the optical effects. The multicoat paint systems maytherefore be used with advantage for the OEM finishing and refinish oftop-class automobiles. The coating materials of the inventionadvantageously contain based on their total amount between 0.25 and 20%by weight of pigment paste.

EXAMPLE

Preparation of a Pigment-Free Coating Composition B1

57.4 kg of an aqueous binder mixture were combined with 12.3 kg of anaqueous melamine resin suspension and 1.8 kg of an acrylic resinaddition.

This mixture was then further admixed with a total of 6 kg of customaryadditives, 1 kg of a commercially customary flatting paste, and 3 kg ofa talc paste, and the components were intimately mixed. Finally, 4.5 kgof water and 0.5 kg of polyurethane thickener were added and the mixturewas again stirred.

Preparation of an Inventive Pigment Paste B2

The pigment paste of the invention was prepared as follows (the % are byweight):

First of all, 1.8 kg of water (15%) were mixed with 0.21 kg of ViscalexHV30 (1.75%). Then a further 4.68 kg of water (39%) were added, followedby 0.26 kg of 10% strength dimethylethanolamine solution (2.17%). Afterthat, 0.7 kg of surfynol (5.83%) and 0.25 kg of Hydropalat 3037 (2.1%)were added.

The whole mixture was then stirred for 20 minutes. Thereafter, 4.1 kg of65% chromated aluminum paste (34.15%) were added and the resultantmixture was stirred for a further 30 minutes.

Preparation of a Pigmented Coating Composition B3

12% by weight of the inventive pigment paste B2 were added to 86% byweight of the pigment-free coating composition B1 and the twoconstituents were mixed thoroughly with the addition of 2 kg of water(2%).

The resulting pigmented coating composition was substantially free fromsolvents, had very good transport properties, and exhibited anoutstanding stability on storage.

1. An aqueous pigment paste that is stable, transportable, and storablefor up to three months, comprising (A) from 15 to 40% by weight of atleast one metal pigment, (B) from 0.45 to 0.75% by weight of at leastone nonassociative thickener comprising at least one methacrylatecopolymer based on C₁-C₆ alkyl (meth)acrylate and (meth)acrylic acid,(C) from 0.1 to 0.4% by weight of at least one organic amine, (D) from0.5 to 8% by weight of at least one nonionic surfactant, and (E) atleast 50% by weight of water, based on total weight, wherein the aqueouspigment paste is free from binders, including grinding resins used fordispersing pigments, wherein the aqueous pigment paste is usable forproducing an aqueous coating material by mixing the aqueous pigmentpaste with at least one aqueous mixing varnish comprising at least onewater-soluble, water-dispersible, or water-soluble and water-dispersiblebinder.
 2. The paste of claim 1, wherein the thickener (B) comprises incopolymerized form at least two different C₁-C₆ alkyl (meth)acrylatemonomers.
 3. The paste of claim 1, wherein the thickener (B), based onits total weight, comprises from 40 to 60% by weight of methacrylic acidin copolymerized form.
 4. The paste of claim 1, wherein the organicamine (C) is selected from the group consisting of tertiary amines. 5.The paste of claim 4, wherein the tertiary amine (C) is selected fromthe group consisting of hydroxyalkylamines.
 6. The paste of claim 5,wherein the hydroxyalkylamine (C) is dimethylethanolamine.
 7. The pasteof claim 1, wherein the metal pigment (A) comprises an aluminum pigment.8. The paste of claim 1, comprising at least 52% by weight of water,based on total weight.
 9. The paste of claim 1, comprising (A) 34% byweight of an aluminum pigment, (B) 0.53 by weight of a nonassociativethickener comprising at least one methacrylate copolymer based on C₁-C₆alkyl (meth)acrylate and (meth)acrylic acid, (C) 0.22% by weight of anorganic amine, (D) 0.61% by weight of a nonionic surfactant, and (E) 54%by weight of water, based on total weight.
 10. A method of preparing acoating material, comprising adding an aqueous pigment paste free frombinders and grinding resins, as claimed in claim 1, to prepare anaqueous coating material comprising the metal pigment.
 11. The method ofclaim 10, wherein the aqueous coating materials are aqueous basecoatmaterials.
 12. A method for making a multicoat paint system, comprisingapplying the aqueous coating material of claim 10 to a substrate.
 13. Aprocess for preparing an aqueous coating material comprising at leastone effect pigment, comprising mixing at least one pigment paste with atleast one aqueous mixing varnish comprising at least one water-solubleand/or -dispersible binder and homogenizing the resulting mixture,wherein the at least one pigment paste comprises at the least oneaqueous pigment paste free from binders and grinding resins, as claimedin claim 1, and is used in an amount such that the resulting mixturefrom 0.1 to 6% by weight of at least one metal pigment (A), and from0.02 to 2.4% by weight of at least one nonionic surfactant (D), based ontotal weight.
 14. The process of claim 13, wherein the binder isselected from the group consisting of random (co)polymers, alternating(co)polymers, block (co)polymers, linear (co)polymers, branched(co)polymers, comb addition (co)polymers, (co)polymers comprisingethylenically unsaturated monomers, polyaddition resins,polycondensation resins, and combinations comprising at least two of theforegoing.
 15. The process of claim 14, comprising at least one memberselected from addition (co)polymers of ethylenically unsaturatedmonomers selected from the group consisting of (meth)acrylate(co)polymers, partially hydrolyzed polyvinyl esters; polyaddition resinsselected from the group consisting of polyesters, alkyds, polyurethanes,polylactones, polycarbonates, polyethers, epoxy resin-amine adducts,polyureas, polyamides, polyimides, polyester-polyurethanes,polyether-polyurethanes, polyester-polyether-polyurethanes andcombinations of at least two of the foregoing; polycondensation resinsselected from the group consisting of polyesters, alkyds, polyurethanes,polylactones, polycarbonates, polyethers, epoxy resin-amine adducts,polyureas, polyamides, polyimides, polyester-polyurethanes,polyether-polyurethanes, polyester-polyether-polyurethanes andcombinations of at least two of the foregoing; and combinations of atleast two of the foregoing.
 16. An aqueous pigment paste that is stable,transportable, and storable for up to three months, comprising (A) from15 to 40% by weight of at least one aluminum metal pigment, (B) from0.45 to 0.75% by weight of at least one nonassociative thickenercomprising at least one methacrylate copolymer based on C₁-C₆ alkyl(meth)acrylate and from 40 to 600% by weight of (meth)acrylic acid incopolymerized form, based on the total weight of the nonassociativethickener, (C) from 0.1 to 4% by weight of at least one organic amine,(D) from 0.5 to 8% by weight of at least one nonionic surfactant, and(E) at least 50% by weight of water, based on total weight, wherein theaqueous pigment paste is free from grinding resins used for dispersingpigments, and other binders, wherein the aqueous pigment paste is usablefor producing aqueous coating materials by mixing the aqueous pigmentpaste with at least one aqueous mixing varnish comprising at least onewater-soluble, water-dispersible, or water-soluble and water-dispersiblebinder.